Had a very strange thing happen yesterday..Driving her as always when a sudden change in the sweet sounding accufab occurs upon acceleration? Inspection reveals a cracked catalyst on the driver's side. That's right cracked in half..Bought my car from a collector who put 100 miles in 11 months..sat alot...My car has custom suspension package coilovers, lowered, billet front ball joints and hardened motor and tranny mounts. The car vibrates alot more but very tolerable to me with a significant increase in tightness and response..My question for the force that lives within our forum....would these rather extreme changes cause this? The car sitting in the previous owners garage contribute to this? My next question is can the cat be replaced without taking the rear of the car off or should I start considering an exhaust, clutch upgrade? Any help for a lifer
cracked cat
- Thread starter Black 907
- Start date
BlackICE
GT Owner
The hardened motor and transaxle mounts have me concerned. The motor, transaxle and exhaust system are designed to move during operation. The mount stiffness are part of the design. Changing the mounts can induce vibrations that the exhaust system was not designed for.
The cats can be changed fairly easily after removing the Accufab pipes. I would suggest you use the stock mounts.
The cats can be changed fairly easily after removing the Accufab pipes. I would suggest you use the stock mounts.
I knew that something like this could happen.have 2000 miles on the set up. I love the handling and intense sensations gained so much...that I was hoping for a solution rather than go back to stock ..would the ford racing exhaust or some other combination prevent this again? Have I finally gone to far?
- Aug 25, 2006
- 4,436
Without seeing pictures and physically confirming the increased vibrations and even more so harmonics created it is speculation at best nevertheless I suspect that you are stressing several components.
Takes care
Shadowman
BTW what is the story behind the billet ball joints?
Hey Bill..thanks for the reply. I was wondering which components you think will be affected negatively. I love the intense sensation and increase in my perceived handling ability brought out with the hardened mounts..but I do not what these types of problems or worse. can I keep these changes without serious damage to structural integrity? The billet front joints were fabricated to quell any bumpsteer keeping tire patches more flat with my extreme lowering at least that is what I was told..All I can say is the car now tracks amazingly over all surfaces without any bumpsteer what so ever. I know these changes are extreme but WOW..So what do you think? Should I return to stock mounts? Just love this set up but would not like future problems.. Thanks for the replies, comments or death threats
SLF360
GT Owner
You are sure to see a difference, or just in your imagination !? Did you drive a regular GT to compare this, or ... ?:eek
STORMCAT
GT
G. I am going to say this can be attributed to your solid motor mounts. The motor mounts are like shock absorbers that will reduce the transmission of all types of vibration. The Cats are constructed of a thin gage SS material. They probably fatigued under the high heat and vibration and probably not corrosion.. my 2 cents.. :biggrin
STORMCAT
GT
G,
You know what I think of this set up .. :bored If I recall I had mentioned my concerns about the vibrations and torque transfer issues prior to this move.. I am not an I told you so kinda of guy ... :biggrin Yes, I know you are crazy but I love ya anyway man.. :biggrin
STORMCAT
GT
G,
I would just go back to the Stock motor and tranny mounts..Your suspension is fine. The GT guys are coming to my shop in early October...:wink They could help you out..:thumbsup . I can hook something up to your seat to make it vibrate...:lol
- Aug 25, 2006
- 4,436
You are welcome
Now what the cause and affect of the changes that you made will be over time are unknown.
I suspect that creating a solid mounting system has transfered stress to areas that were never intended to receive it; now whether this along will cause future failures is anyone's guess with the gal in full operational trim.
So would I leave the engine and transmission munts as solids; no. I think that the unknown elements are simply to great however you playing is this arena is what making a gal your own is all about as such if you continue on this path just do so with your eyes and potentially your wallet open.
Now how did the billet ball joints further (because the build team did a fine job) reduce bump-steer? Are they raised, lowered, offset, or ?
Lastly; with regards to the cat failure, please share a picture when time permits because I have never seen one split as you have described.
Takes care
Shadowman
TifosiTed
GT Owner
Black907,
I tend to agree with Shadowman regarding the changed harmonics causing a fatigue issue.
If you want to keep your set up and don't want to keep replacing the stock cats, maybe consider changing out the exhaust system to the Stainless Works headers with the small metal cats. The lower weight of the system might drive the forcing function interference into a higher frequency thereby eliminating the fatigue issue in the cats.
But who knows where/if the next fatigue issue will show up?:ack
I tend to agree with Shadowman regarding the changed harmonics causing a fatigue issue.
If you want to keep your set up and don't want to keep replacing the stock cats, maybe consider changing out the exhaust system to the Stainless Works headers with the small metal cats. The lower weight of the system might drive the forcing function interference into a higher frequency thereby eliminating the fatigue issue in the cats.
But who knows where/if the next fatigue issue will show up?:ack
again thanks for entertaining such craziness. It was incredible while it lasted...but I know you are right and the GT GUYS just happen to be coming my way in SFLA. So back to stock they go... better to be safe than sorry in the future. I discussed the billet joints with Rich as well. My car is lowered 1 1/2 inches in front and 1 inch in rear. I drove another car without the changes and it was easy to throw the car off line. Now tracks perfect no matter what surface...so I guess I will keep those..what about an exhaust upgrade. Will those like on Shoboat's car eventually make you deaf? afterall I am extreme...thanks again for any imput from the powers within
BlackICE
GT Owner
I am curious to what characteristics were sought with the solid motor and transaxle mounts. I can understand the ball joints, since that changing the ride height can alter bumpsteer, due to Ford designing bumpsteer to be minimal at the stock ride height.
I agree with Shadowman that the feedback here is largely speculation since you may be "pioneering" some new variables.
That being said, I wouldn't have guessed that a cat structural failure would be a symptom that you would see before any others. The back of the cats, as you may be aware, are attached to a thin band strap that allows the cats to grow and shrink with the different temperatures that they see. As they are not bound rigidly, I would doubt that they are under any real stress. However, harmonics can be a funny thing and it could be the case that this is what has bitten you. However, my view is that this too is unlikely.
As you have an Accufab exhaust, I would ask you to inspect the small gusseted bracket that secures the exhaust to the aforementioned strap. I have seen a few of the welds break around the gusset which causes the entire cat and exhaust to cantilever off of the ball flange at the front of the cat. When this happens, the cat itself is stressed and a failure would be likely.
So, if I was a betting person, I would say that there is a possibility that this support brace failed first and perhaps went unnoticed. Without correction, the failure that you had would not be unlikely.
If this is found to be the case, I would improve the design of the Accufab support brace and then have a qualified TIG welder repair the CAT. I would remain with this setup if it is something you like and enjoy.
I am very thankful for the great bunch of guys in our forum. I think the accufab brackets also were loose but I did not see any evidence of cracking. Although in my last GT they did and had to be welded. This sounds like the cause good detective work makes sense. However, I would love to keep this set up as it makes the car intensly visceral and invigorating... but as you noted..this is virgin territory who knows what the future may bring so I am really torn.. I also thought of changing out the exhaust to a lighter weight flow through, but the question remains..does anybody know what else could happen..Rich GT GUY mentioned possible cracking of a chassis weld no fun at all..but who knows.. so my turmoil continues..I think for piece of mind and a long healthly life... stock may be the answer...
what a great life we have with our GTs..
thanks again to all and I welcome all comments from you guys as they really help put things in perspective
what a great life we have with our GTs..
thanks again to all and I welcome all comments from you guys as they really help put things in perspective
Loose is not good in that it would allow vertical movement of the aft end of the cats and the exhaust. This is the cantilevering effect off of the front ball flange joint where the cats mate to the cast manifolds. Such cantilevering force could stress the cat and cause it to crack/split.
Other exhaust options are more expensive but may be no more robust in addressing the set-up that you like to run. Although some may be lighter, they fundamentally use the same method for mounting. I would think that header tubes may be more susceptible to fatigue/failure than the OEM cast iron set-up you have now.
One option you should consider is replacing your stock cats with the Ford Racing Cat Delete Pipes. These are lighter than the cats and I would recommend you to consider having them jet-coated to further reduce heat. (I run these on my car and like them a lot.)
I also thought of the ford racing cat delete pipes..are you running an accufab as well. I fiqured that if I was choosing those.. just go to the extreme as I have already and go with the long tube headers. I know they are loud but as you can tell..I'm sick..
Thanks to the information gathered from our great forum members.. I was able to have an intelligent extensive conversation with the mechanics that put together my set up. I found out that they are running four cars with the same set up. The guy I met runs his car extremely hard and has a large wipple with the ford racing exhaust. He has 4000 miles without difficulty..I . drive my car hard enough but in no way like the abuse that I witnessed. So again my turmoil..love the set up...isn't life grand..anyone using the ford racing exhaust? would love to hear some feedback..you know from one sicko to another...
Thanks to the information gathered from our great forum members.. I was able to have an intelligent extensive conversation with the mechanics that put together my set up. I found out that they are running four cars with the same set up. The guy I met runs his car extremely hard and has a large wipple with the ford racing exhaust. He has 4000 miles without difficulty..I . drive my car hard enough but in no way like the abuse that I witnessed. So again my turmoil..love the set up...isn't life grand..anyone using the ford racing exhaust? would love to hear some feedback..you know from one sicko to another...
Nota4re
just read your post closer..the long tube headers are one piece right? they also mount in a similar way? How much labor is involved with the cat delete install and what exhaust are you running with them..I am not the most mechanical person so all these concepts are alittle new to me..thanks for the education in GT 101 knowledge is power...
just read your post closer..the long tube headers are one piece right? they also mount in a similar way? How much labor is involved with the cat delete install and what exhaust are you running with them..I am not the most mechanical person so all these concepts are alittle new to me..thanks for the education in GT 101 knowledge is power...
The M-9430-GTX Rear Exit Headers are a 2-piece construction, the two pieces held together by 3 springs at the interface joint about ½ way from the exhaust ports to the collector.